In the prior art, a fish finder equipped with an ultrasonic transmitter has been well known. The prior art transmitter issues an acoustic wave into water and receives a counter echo which shows the existence of fish in the water.
On the other hand, a hand-held LCD (Liquid Crystal Display) game machine has been also very popular. This machine is operated with both thumbs of a player after a cartridge with its memory cell having a memory of a program data is inserted into the machine.
The prior fish finder in general is large in size and heavy in weight. Its operation is very complicated in use and also the finder is an expensive apparatus. These situations make it difficult for lovers of fishing to prepare a fish finder by themselves.
Accordingly, it has been for a long time desired by them that a new fish finder in light weight, inexpensive in price, and with easier operation shall be realized.
The hand-held LCD game machine is actually sold in a very competitive price, and its operation is far easier than that of the normal fish finder for everyone. Thus, everyone is becoming familiar with this kind of the machine and is willing to operate the same by himself.